Which of the following best describes a percentage lease?

A percentage lease is characterized by rent that fluctuates based on the tenant's sales revenue, making option C the correct choice. This type of lease is commonly used in retail spaces where the landlord receives a percentage of the tenant's sales as part of the rental agreement. Such an arrangement aligns the interests of both the landlord and tenant; as the tenant's sales increase, so does the rental income for the landlord. This can motivate landlords to support the success of their tenants, fostering a mutually beneficial relationship.

The other options misrepresent what a percentage lease entails. A lease with a fixed or flat rate does not vary with sales performance, thus failing to qualify as a percentage lease. Adding maintenance fees relates to other lease types or stipulations, but it does not define a percentage lease. Lastly, the absence of a specified duration is unrelated to the concept of a percentage lease, as these leases can very well have defined terms while still incorporating the sales-based rent structure.